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• Serpentine channel with multi-dimensional blocks are proposed. • Positive effects result from corner blocks creating forced convection at the bend. • Novel flow field provides high current density and enhance mass transfer. • Vertical flow velocity is impacted by the change in block angle. • Verify the performance trend of selected corner blocks through experiments. The geometric modification of the flow field is an effective measure to improve the performance of proton exchange membrane fuel cell (PEMFC) and the mass transfer ability of reactants. In this paper, serpentine channels with geometric parameters containing various blocks to generate gas forced convection at the U-bends are established and numerically studied. Setting blocks at different angles at U-bends has different effects at the corners, offering a more flexible and variable region of active gas diffusion in the vertical direction. The area of high vertical velocity is increased by the Angle-Height combination design with low pressure drop and uniform temperature distribution. It is demonstrated that a vertical velocity of 0.4 m s−1 can be achieved around the block in the 135° series with half-height corner blocks, proving the existence of the mass transfer enhancement. Subsequently, experimental testing is conducted to verify the feasibility of the optimized flow field. The experimental results support the trend of block height influencing cell performance, with a maximum power density increase of 3.4 %. Modifying the U-bend corner structure has proven to be an effective technique for improving the overall performance of PEMFC, which can serve an important guidance for future flow field design. [ABSTRACT FROM AUTHOR]

Abstract: Compared to immobilized lipase, soluble lipase has the merits of lower cost and faster reaction rate, thus much attention has been paid to soluble lipase-mediated methanolysis for biodiesel (fatty acid methyl ester, FAME) production in recent years. Our previous study showed that soluble lipase NS81006 could effectively catalyze the methanolysis of soybean oil (triglyceride, TG) for FAME preparation in oil/water biphasic system. Study on the related mechanism of soluble lipase NS81006-mediated methanolysis of TG was carried out in this paper. Based on the analysis of substances change in the reaction process, mechanism model was hypothesized and the model parameters were simulated by Matlab. The simulated model was validated further. The results showed that in the reaction process of soluble lipase NS81006-mediated methanolysis of TG in oil/water biphasic system, TG proceeded three-step hydrolysis to generate FFA (free fatty acid), and then FFA transformed into FAME by esterification with methanol. During the whole process, FFA is mainly generated through the hydrolysis of TG and intermediate DG (diglyceride), while the hydrolysis of FAME could be ignored. [Copyright &y& Elsevier]